Composition for bottom reflection preventive film and novel polymeric dye for use in the same

ABSTRACT

As a bottom anti-reflective coating material for use in photolithography, polymer dyes represented by following general formula are used. The polymer dyes are able to form a bottom anti-reflective coating having good film formation properties, good absorption properties at exposure wavelength, good step coverage, non-intermixing with photoresist and high etch rate.                    
     wherein 
     R represents H or a substituted or non-substituted alkyl, cycloalkyl, or aryl group, R 1  represents a substituted or non-substituted alkyl or aryl, or a —COOR 3  group in which R 3  represents an alkyl group, R 2  represents a substituted or non-substituted alkyl, cycloalkyl, or aryl group, D is an organic chromophore which absorbs at the exposure wavelength (150-450 nm) and represents a substituted or non-substituted aryl, condensed aryl, or heteroaryl group, m and o are any integer above zero, and n, p and q are any integer including zero.

TECHNICAL FIELD

This invention relates to a novel composition for a bottomanti-reflective coating composition, a method of forming a bottomanti-reflective coating between a substrate and a photoresist layerusing the bottom anti-reflective coating composition and manufacturingintegrated circuits utilizing a photolithography method, and novelpolymer dyes. More particularly this invention relates to a compositionfor a bottom anti-reflective coating comprising at least a solvent and anovel polymer dye having recurrent cyclic acetal units, and a method offorming a bottom anti-reflective coating by using the composition andmanufacturing integrated circuits by utilizing a photolithographymethod, novel polymer dyes, and a method of producing thereof.

BACKGROUND ART

In manufacturing integrated circuits and active elements andinterconnecting structures within microelectronic devices, aphotolithography technique using photoresist compositions is utilized.In general the manufacturing of the integrated circuits ormicroelectronic devices are conducted as followed. That is, first, aphotoresist material dissolved in a solvent is applied on a substratesuch as silicon wafer by spin coating. The substrate coated with resistis then baked at elevated temperatures to evaporate any solvent in thephotoresist composition and to form a thin photoresist layer with goodadhesion to the substrate. The thin photoresist layer on the wafer wassubjected to an imagewise exposure to radiation in the range of 150 to450 nm wavelength, such as visible or ultraviolet (UV) rays. Theimagewise exposure may also be conducted by electron beam or X-rayradiation in place of such visible or UV rays. In the exposed areas ofthe photoresist layer the chemical transformation arises by theexposure. After the imagewise exposure, the substrate with an imagewiseexposed resist layer was subjected to developing process using analkaline developer to dissolved out either the unexposed(negative-working resist) or exposed (positive-working resist) areas.The opened areas on the substrate formed by dissolving out the resistare subjected to additional unselective processing steps to manufacturefinal integrated circuits or electronic devices.

In manufacturing integrated circuits and the like, the high degree ofintegration has been intended and, in recent years, in order to attain ahigher degree of integration techniques for still more decreasingfeature sizes are required. Therefore lithographic techniques usingconventional near UV, such as g-line (436 nm) and i-line (365 nm) shiftto imaging processes using radiation of shorter wavelength, such asmiddle UV (350-280 nm), or deep UV (280-150 nm). The latter especiallyemploys KrF (248 nm) or ArF (1 93 nm) excimer laser radiation. Excimerlaser radiation sources emit monochromatic radiation. Highly sensitive,excimer laser compatible chemically amplified, positive- ornegative-working deep UV photoresist compositions offering excellentlithographic performance and high resolution capability have becomeavailable recently. Due to their chemical compositions and their imageformation mechanisms, state-of-the-art chemically amplified photoresistcompositions are usually transparent at the exposure wavelength, and donot exhibit a pronounced sensitivity owing to poisoning effects inducedby base contaminants present at the photoresist-substrate orphotoresist-air interfaces, respectively. While appropriate deep-UVexposure tools in combination with the high performing photoresists arecapable of patterning structural elements with dimensions below quartermicron design rules, tendency of arising image distortions anddisplacements due to some optical effects become conspicuous in suchhigh resolution image. Therefor the method of forming resist images notaffected by such optical effects and having good reproducibility arestrongly required.

One of the problems caused by such optical effects is “standing wave”formation which is well known in the art and arise from substratereflectivity and thin film interference effects of the monochromaticradiation. Another problem is “reflective notching” known in the art dueto light reflection effects resulting from highly reflective topographicsubstrates. In single layer resist processes it is difficult to conductthe linewidth uniformity control due to the reflective notching. Certainreflective topographical features may scatter light through thephotoresist film, leading to linewidth variations, or in other case,resist loss. Such problems are extensively documented in the literature,e.g. (i) M. Horn, Solid State Technol., 1991(11), p. 57 (1991), (ii) T.Brunner, Proc. SPIE 1466, p. 297 (1991), or (iii) M. Bolsen et al.,Solid State Technol., 1986(2), p. 83, (1986).

Thin film interference generally results in changes of linewidth byvariations of the substantial light intensity in the resist film as thethickness of the resist changes. These linewidth variations areproportional to the swing ratio (S) defined by following equation (1)and must be minimized for better linewidth control.

S=4(R₁R₂)^(½) e ^(−αD)  (1)

Wherein R₁ is the reflectivity at the resist-air interface, R₂ is thereflectivity of the resist-substrate interface, α is the resist opticalabsorption coefficient, and D represents the resist film thickness.

One of lithographic techniques to overcome the above-mentioned problemsduring pattern formation on reflective topography is addition ofradiation absorbing dyes to the photoresists as described in U.S. Pat.Nos. 4,575,480 or 4,882,260. This corresponds to an increase of theoptical absorption coefficient a in equation (1) above. When a dye isadded to the photoresist to form a radiation sensitive film having highoptical density at the exposure wavelength, drawbacks such as loss ofresist sensitivity, resolution and depth-of-focus capability, contrastdeterioration, and profile degradation are encountered. In addition,difficulties during subsequent hardening processes, thinning of theresists in alkaline developers and sublimation of the dye during bakingof the films may be observed.

Top surface imaging (TS1) processes, or multi layer resist arrangements(MLR) as described in U.S. Pat. No. 4,370,405 may help prevent theproblems associated with reflectivity. However, such methods requirecomplex processes and are not only difficult to control the processesbut also expensive and therefore not preferred. Single layer resist(SLR) processes dominate semiconductor manufacturing because of theirsimplicity and cost-effectiveness.

The use of either top or bottom anti-reflective coatings inphotolithography is a much simpler and effective approach to diminishthe problems that arise from thin film interference, corresponding toeither a decrease of R₁ or R₂ and thereby reducing the swing ratio S.

The most effective means to eliminate the thin film interference is toreduce the through the use of so-called bottom anti-reflective coatings(BARC). These coatings have the property of absorbing the light whichpasses through the photoresist and not reflecting it back. The bottomanti-reflective coating composition is applied as a thin film on thesubstrate prior to coating with the photoresist composition. The resistis then applied on the bottom anti-reflective coating, exposed anddeveloped. The anti-reflective coating in the resist removed areas isthen etched, for example in an oxygen plasma, and the resist pattern isthus transferred to the substrate allowing for further processing stepsfor forming active elements, interconnecting structures etc. The etchrate of the anti-reflective coating composition is of major importanceand should be relatively higher than that of the photoresist, so that itis etched without significant loss of the photoresist film during theetch process.

Bottom anti-reflective coatings are typically divided into two types,namely inorganic and organic bottom anti-reflective coating types.

Inorganic types include stacks of dielectric anti-reflective coatingssuch as TiN, TiON, TiW and spin-on glasses useful in a thickness rangeof below 300 Å. Examples are described by (i) C. Noelscher et al., Proc.SPIE 1086, p. 242 (1989), (ii) K. Bather et al., Thin Solid Films, 200,p. 93 (1991), or (iii) G. Czech et al., Microelectr. Engin., 21, p. 51(1993). Although inorganic dielectric anti-reflective coatingseffectively reduce thin film interference effects, they requirecomplicated and precise control of the film thickness, film uniformity,special deposition equipment, complex adhesion promotion techniquesprior to resist coating, separate dry etching pattern transfer step, andare usually difficult to remove.

Improved linewidth and standing wave control can also be attained by useof organic bottom anti-reflective coating as same as inorganic type. Asorganic bottom anti-reflective coatings it is known ones formulated byadding dyes which absorb at the exposure wavelength to a polymer film,as described by C. H. Ting et al., Proc. SPIE 469, p. 24 (1984), or W.Ishii et al., Proc. SPIE 631, p. 295 (1985). Problems of theanti-reflective coatings produced as described above include (1)separation of dye and polymer during spin coating, drying, or baking,(2) sublimation of the dye during the subsequent hard-bake step, (3) dyestripping into resist solvents, (4) thermal diffusion into the resistupon the baking process and (5) interfacial layer formation. Thesephenomena may cause severe degradation of lithographic propertiesespecially when combined with chemically amplified photoresists andtherefore the method of using dye blended bottom anti-reflectivecoatings are not preferred. Especially problematic is the sublimationissue, as not only the absorption properties of the bottomanti-reflective coating are deteriorated, but also contamination of theexpensive equipment must be anticipated, causing process problems due toincreased particle concentrations at a later stage.

As an alternative, organic bottom anti-reflective coatings containingradiation absorbing pigments have been suggested (EP-A1 744662). Suchbottom anti-reflective coatings may produce a large number of insolubleparticles during device processing and thereby reduce yieldconsiderably.

Direct chemical attachment of dyes to a film forming polymer is anotheroption (US patent 5,525247). The materials disclosed therein are usuallycasted from hazardous organic solvents, such as cyclohexanone orcyclopentanone. M. Fahey et al., Proc. SPIE 2195, p. 422 (1994) describeamino group-containing dyes reacted with the anhydride groups ofpoly(vinylmethylether-co-maleic anhydride). One problem connected withthese types of bottom anti-reflective coating compositions is that thereaction between the amine and the polymeric anhydride groups does notproceed quantitatively thus resulting in the presence of free amines(EP-A1 583,205, p. 5, lines 17-20). The unreacted amine causes poisoningof the resist at the bottom anti-reflective coating-resist interfaceespecially when base sensitive chemically amplified resist compositionsare employed resulting in resist foot formation due to incompletedissolution of the exposed resist bottom layer upon development. Thefree dye molecules may also sublime during the baking process, depositon the fabrication instruments and cause contamination problems as wellas health hazard to the workers. One more disadvantage of these specificcomposition is that imide compounds formed upon the reaction between theamine and the anhydride groups are poor in their solubility and requirepolar solvents for their processing not used normally in photoresistformulations. From the processing standpoint, it would be ideal to usethe same solvent for photoresist and for bottom anti-reflective coating.Furthermore, water which is formed as the by-product of the imidizationreaction may cause coating defects (pinholes) during film formation.

Another system which Fahey et al. propose in the above mentionedpublication is based on materials composed from copolymers of methylmethacrylate and 9-methylanthracene methacrylate. However, formulationsbased on these copolymers usually show footing due to the diffusion ofphoto generated acid into the bottom anti-reflective coating film aswell as intermixing of the resist and the bottom anti-reflective coatingfilm thus limiting their practical use. The copolymers are alsoinsoluble in preferred photoresist solvents such as propylene glycolmonomethyl ether acetate (PGMEA) or ethyl lactate (EL).

U.S. Pat. Nos. 5,234,990 and 5,578,676 describe polysulfone and polyurearesins which possess inherent light absorbing properties at deepultraviolet wavelengths. However, these condensation products havecomparatively poor film forming properties and therefore exhibit poorstep-coverage on topographic substrates, resulting in a problem of imagetransfer to the substrate. In addition, it has been found that thesematerials exhibit a high degree of crystallinity and tend to form cracksprobably due to their high Tg and rigid structures. Initially, a bottomanti-reflective coating should be soft to achieve good step coverageproperties upon coating and in addition should have the ability tocrosslink and harden after baking to prevent intermixing of thephotoresist with the bottom anti-reflective coating layer as well asdiffusion of the photo generated acid.

U.S. Pat. No. 5,554,485 and EP-A1 698823 describe poly(arylether) orpoly(arylketone) polymers respectively. These polymers have a ratherhigh concentration of aromatic units and therefore their etch rates arerather low. That is same for the polyvinylnaphthalene derivativesdisclosed in U.S. Pat. No. 5,482,817.

EP-A1 542008 describes the use of phenolic type resin binders andmelamine type crosslinking agents in combination with either thermal, orphoto acid generators to harden the bottom anti-reflective coating filmafter coating. Such compositions are poor in their storage stability dueto the presence of the crosslinking agents and photo acid generatorsresulting in high film defect yields. In addition, their etch rate isvery low due to the presence of rather large amounts of aromaticfunctional groups.

Japanese Laid-opened Patent Publication No. H10-221855 discloses ananti-reflective coating material composition containing a high molecularcompound in which choromophores having 10,000 or more of molarextinction coefficient for either 365 nm, 248 nm or 193 nm wavelengthradiation are linked to at least a part of alcohol moieties of recurrentvinyl alcohol units in main chain and a method of producing resistpatterns. However introduction of such bulky polycyclic aromatic groupalone into a high molecular compound containing recurrent vinyl alcoholsuch as polyvinyl alcohol by acetalization reaction requires elevatedtemperature and long time reaction. In addition it is difficult toattain high reaction percentage. The publication disclose that expectedyield is attained when the reaction was conducted in dioxane at 100° C.for 40 hours. However the organic chromophore groups are easy todecompose under such reaction conditions and it is necessary to moderatethe reaction conditions.

In summary, a superior bottom anti-reflective coating material shouldsatisfy the following requirements:

a) good film forming property

b) high absorption at the applied exposure wavelength

c) no intermixing with the photoresist

d) high etch rate compared with the photoresist

e) good step coverage on topography

f) practical storage stability

g) compatibility with and solubility in photoresist and edge-bead rinse(EBR) solvents

h) adaptability to several commercial resists

i) ease of production and high yield.

The object of the present invention is to provide an anti-reflectivecoating composition satisfying above preferable properties, a method ofmanufacturing integrated circuits using the composition, novel polymerdyes and a method of preparing thereof.

Definitely, the first objective of the present invention is to provide abottom anti-reflective coating composition which absorbs radiation inthe wavelength range of 150-450 nm thus eliminating problems associatedwith light reflected from the substrate and topography during patternformation.

The second objective of the present invention is to provide a bottomanti-reflective coating composition having improved adhesion tointegrated circuit or micro-electronic substrates, very good coatinguniformity and showing no particle formation.

The third objective of the present invention is to provide a bottomanti-reflective coating composition with a superior etch rate thancurrent available bottom anti-reflective coatings, having improvedcompatibility with the existing chemically amplified photoresists, andgenerating neither undercut nor footing.

The fourth objective of the present invention is to provide novelpolymeric dyes having cyclic acetal moieties and applicable for a bottomanti-reflective coating composition as well as producible easily and inhigh yield and a method of preparing thereof.

The fifth objective of the present invention is to provide bottomanti-reflective coating compositions comprising of polymeric dyes havingcyclic acetal moieties, together with, if necessary, crosslinking agentsand other additives such as photo acid generators, plasticizers orsurfactants.

The sixth objective of the present invention is to provide novel polymerand copolymer materials producible easily and in high yield, and capableof curing (crosslinking) at the baking temperatures of the resultingbottom anti-reflective coating to harden the bottom anti-reflectivecoating thus providing a barrier for photoresist solvent or componentpenetration and thereby preventing foot formation caused by eitherintermixing or acid diffusion.

The invention further provides a method for application and use of theanti-reflective coating composition in combination with a photoresist ona substrate useful in manufacturing integrated circuits andmicro-electronic devices. Thus in a preferred aspect, a method isprovided, comprising the steps of; 1) treating a substrate with aprimer, 2) applying the bottom anti-reflective composition of thepresent invention, 3) baking the coated bottom anti-reflective coatingfilm to evaporate the solvent and to harden the film, 4) applying aphotoresist on top of the bottom anti-reflective coating, 5) drying thephotoresist, 6) exposing the photoresist using a mask, 7) developing theresist and 8) removing the bottom anti-reflective coating in the openedareas.

Other objects will become apparent from the following detaileddescription, preferred embodiments and illustrative examples mentionedbelow.

DISCLOSURE OF THE INVENTION

It was found that the objects of the invention described above were ableto be attained by using an anti-reflective coating compositioncomprising at least a solvent and a novel polymer dye with cyclic acetalunits.

That is, the present invention provides a bottom anti-reflective coatingcomposition comprising at least a solvent and a polymer dyes asrepresented by general formula 1:

wherein

R represents a hydrogen atom, a substituted or non-substituted C₁-C₂₀alkyl group, a substituted or non-substituted C₆-C₂₀ cycloalkyl group,or a substituted or non-substituted C₆-C₂₀ aryl group,

R¹ represents a hydrogen atom, a substituted or non-substituted C₁-C₅alkyl group, a substituted or non-substituted C₁-C₁₀ aryl group, or a—COOR³ group in which R³ represents a C₁-C₁₀ alkyl group,

R₂ represents a substituted or non-substituted C₁-C₅ alkyl group, asubstituted or non-substituted C₆-C₂₀ cycloalkyl group, or a substitutedor non-substituted C₆-C₂₀ aryl group,

D is an organic chromophore which absorbs at the exposure wavelength(150-450 nm) and represents a substituted or non-substituted C₆-C₃₀ arylgroup, a substituted or non-substituted C₆-C₃₀ condensed aryl group, ora substituted or non-substituted C₄-C₃₀ heteroaryl group,

m and o are any integer above zero, and

n, p and q are any integer including zero.

Further the present invention provides a method of forming a bottomanti-reflective coating on a semiconductor substrate such as siliconwafer in which the above mentioned bottom anti-reflective coatingcomposition is spin-coated on the substrate and baked to evaporate thesolvent; and a bottom anti-reflective coating formed by the method.

Further the present invention provides a method of manufacturing anintegrated circuit in which a positive-working or negative-workingphotoresist sensitive to radiation in the range of 150 nm-450 nmwavelength is applied onto the above mentioned bottom anti-reflectivecoating on the substrate, exposed to radiation, developed, and then wetor dry etched to transfer the image.

Further more the present invention provides novel polymer dyesrepresented by the general formula 1.

The novel polymer dyes represented by the general formula 1 are preparedby the reaction of polyvinyl alcohol or derivatives thereof and anaromatic chromophore having an aldehyde group which absorbs theradiation in the range of 150-450 nm wavelength. The film formingcomposition containing the polymer dye of the invention can absorbradiation in the range of 150-450 nm wavelength. It contains optionallyadditives such as a crosslinking agent, a thermal or photo acidgenerator, a plasticizer, and a surfactant. The bottom anti-reflectivecoating composition of the present invention is utilized formanufacturing integrated circuits due to preventing the problems causedby reflection or scattering of the radiation in lithography process.

The bottom anti-reflective coatings of the present invention are basedon radiation absorbing dyes directly attached via cyclic acetal linkagesto a vinyl alcohol type polymer backbone. In accordance with the presentinvention, the polymer dyes represented by the general formula 1 can besynthesized starting from, for example, a partially or fully hydrolyzedpolyvinyl alcohol, poly(vinyl alcohol-co-ethylene), poly(vinylacetal-co-vinyl alcohol), poly(vinyl acetal-co-vinyl alcohol-co-vinylacetate), or partially hydrolyzed vinyl acetate-co-acrylate blockcopolymers and the respective chromophore-containing aldehyde compound.Reactions in synthesis examples described below proceed typically inaccordance with following reaction schemes. As outlined in reactionscheme 1, polyvinyl alcohol is subjected to the parallel reaction withan aldehyde derivative R—CHO and a radiation absorbing carbonylchromophore D—CHO. In reaction scheme 2, polyvinyl alcohol partiallyreacted with an aldehyde is used as the starting material andsubsequently reacted with a radiation absorbing chromophore D—CHO:

wherein

R represents a hydrogen atom, a substituted or non-substituted C₁-C₂₀alkyl group, a substituted or non-substituted C₆-C₂₀ cycloalkyl group,or a substituted or non-substituted C₆-C₂₀ aryl group,

D is an organic chromophore which absorbs at the exposure wavelength(150-450 nm) and represents a substituted or non-substituted C₆-C₃₀ arylgroup, a substituted or non-substituted C₆-C₃₀ condensed aryl group, ora substituted or non-substituted C₄-C₃₀ heteroaryl group, and m, n and oare integers between 5 and 50,000.

wherein

R represents a hydrogen atom, a substituted or non-substituted C₁-C₂₀alkyl group, a substituted or non-substituted C₆-C₂₀ cycloalkyl group,or a substituted or non-substituted C₆-C₂₀ aryl group,

D is an organic chromophore which absorbs at the exposure wavelength(150-450 nm) and represents a substituted or non-substituted C₆-C₃₀ arylgroup, a substituted or non-substituted C₆-C₃₀ condensed aryl group, ora substituted or non-substituted C₄-C₃₀ heteroaryl group, and m, n and oare integers between 5 and 50,000.

Both reactions shown in schemes 1 and 2 are classified as acetalizationreactions showing the use of aldehydes R—CHO and D—CHO, respectively, asreactants. It is well known to those skilled in the art, that eitherketones (ketalization reaction) such as R—CR⁴O and D—CR⁴O, alkyl acetals(transacetalization reaction) such as R—CH(OR⁵)₂ and D—CH(OR⁵)₂, alkylketals (transketalization reaction) such as R—CR⁴(OR⁵)₂ and D—CR⁴(OR⁵)₂or enolethers (wherein R and D have the same meaning as described above,R⁴ has the same meaning as R, and R⁵ represents a C₁-C₄ alkyl group.)may serve for the same purpose. It should be noted however, that the useof aldehydes is preferred over that of the other compounds mentionedabove due to their availability and ease of reaction.

The reactions as shown in schemes 1 and 2 require acid catalysts. Anystrong acid such as sulfuric acid, nitric acid or hydrochloric acid canbe used. Acidic ion-exchange resins such as Amberlyst (trade name,supplied by Fluka A,G.) may also be applied as catalysts. The use ofacidic ion-exchange resins has the advantage of obtaining a finalproduct free from acidic impurities since the catalyst can be removedfrom the reaction mixture by filtration techniques.

The weight average molecular weight (Mw) of the polyvinyl alcohol usedin reaction schemes 1 and 2 may range generally between 500 and5,000,000. Considering the film forming properties and the solubilitycharacteristics, preferred weight average molecular weights are between2,000 and 100,000.

Useful radiation absorbing chromophores D include the following groupsbut are by no means limited to these examples: phenyl, substitutedphenyl, benzyl, substituted benzyl, naphthyl, substituted naphthyl,anthracenyl, substituted anthracenyl, anthraquinonyl, substitutedanthraquinonyl, acridinyl, substituted acridinyl, azophenyl, substitutedazophenyl, fluorenyl, substituted fluorenyl, fluorenonyl, substitutedfluorenonyl, carbazolyl, substituted carbazolyl, N-alkylcarbazolyl,dibenzofuranyl, substituted dibenzofuranyl, phenanthrenyl, substitutedphenanthrenyl, pyrenyl, and substituted pyrenyl. The substitutions inthe above mentioned dye molecules can include one or more of thefollowing groups: linear, branched or cyclic C₁-C₂₀ alkyl, C₆-C₂₀ aryl,halogen, C₁-C₂₀ alkyloxy, nitro, carbonyl, cyano, amide, sulfonamide,imide, carboxylic acid, carboxylic acid ester, sulfonic acid, sulfonicacid ester, C₁-C₁₀ alkylamine, or C₆-C₂₀ arylamine.

Suitable examples of R—CHO in reaction scheme 1 include, but are notlimited to formaldehyde, acetaldehyde, propionaldehyde, butylaldehyde,benzaldehyde, substituted benzaldehyde, p-hydroxybenzaldehyde,p-methoxybenzaldehyde, and the like.

The selection of the organic solvent in which the reaction betweenpolyvinyl alcohol and the carbonyl compound is performed is not criticalprovided it is not basic in nature. Preferred solvents include methanol,ethanol, isopropanol, propylene glycol monomethyl ether, ethyl lactate,or glycol. Most preferred is the use of ethanol as the solvent andsulfuric acid as the acid catalyst.

The matters described hereinbefore can be applicable for partiallyhydrolyzed polyvinyl alcohols containing other recurrent unit except forvinyl alcohol or copolymers containing other recurrent units except forvinyl alcohol and vinyl acetate. By selection of recurrent unit exceptfor vinyl alcohol, regulation control of solubility of polymer dye insolvent, glass transition temperature of polymer dye, melt viscosity ofpolymer dye, affinity of polymer dye for resist, surface unity inapplication, or flattening can be conducted.

Some specific examples of monomer forming other recurrent unitcontaining R¹ group include ethylene, propylene, acrylates such asmethylacrylate, styrene, styrene derivatives, and the like. Examples ofgroup R² include typically methyl, ethyl, propyl or butyl group andmethyl group is preferred.

The molar ratios of the components m and o in the general formula 1depend on the amount of D—CHO and R—CHO reacted with polyvinyl alcohol.This ratio also determines the absorption coefficient ‘k’ of the polymerdye as well as its solubility. It is necessary to have a sufficientamount of m in order to obtain bottom anti-reflective coatingcompositions capable of suppressing the standing waves. The absorptionat the targeted wavelength and the refractive index of the final polymerplay an important role in the applicability of the material for bottomanti-reflective coatings. Absorption values of the bottomanti-reflective coating in the range of 2 to 40 per micron filmthickness is desired and values between 5 and 15 per micron areespecially preferred and should be maintained in the copolymers as well.Both, too high absorption and too low absorption may lead to inferiorperformance of the bottom anti-reflective coating. However, there are nooptimum absorption and refractive index values for a bottomanti-reflective coating material as these values also depend on theabsorption and refractive index of the photoresist material applied onit. The refractive index of the bottom anti-reflective coating would beoptimum if it exactly matches that of the resist layer applied on top.Although the absorption properties of the bottom anti-reflective coatingare settled in substance by the molar ratio, the range of the molarratio may be changed by the molar extinction coefficient of D. Theabsorption of the anti-reflective coating can be further optimized for acertain wavelength by the selection of suitable substituents on the dyefunctionality D. Electron withdrawing or electron donating substituentsusually shift the absorption wavelength to shorter or longer wavelength,respectively. Similarly, an appropriate choice of substituents on any ofthe monomer units can enhance the solubility or crosslinking property ofthe polymer.

When the acetalization reaction is conducted by using aldehydederivatives, R—CHO and D—CHO described hereinbefore, the uniformity ofthe reaction mixture is better than that of reaction system not usingR—CHO. In addition, the reaction in the mixture solution proceeds atrather low temperature such as about 70° C. and fully for shorter timesuch as 8-10 hours and the reaction products are obtained in high yieldintended. These are preferable from the standpoint of reaction mechanismand protection of chromophores. In the method of producing polymer dyesusing two aldehyde derivatives of the present invention, pluralchromophores can be bonded to polymer chain. One polymer bonded byplural choromophores can be applicable for two different exposurewavelength radiations. The example thereof is described in Example 7mentioned below, wherein a polymer dye absorbing at wavelengthradiations of both 248 nm KrF laser and 193 nm ArF laser is used. Thisis clearly different from the technique described in JP-A H10-221855which does not use aldehyde derivative, R—CHO in production of polymerdyes and is one of main distinctive points of the present invention.

Molar ratios of the components n, p and q in the general formula 1 areany integer containing zero and these values are selected suitablyaccordance with the properties required to the polymer dye. For exampleeither p or q may be zero or both p and q may be zero.

The preferred examples of the range of these m, n, o, p and q are,m=0.20-0.90, n=0.05-0.30, o=0.01-0.40, p=0-0.40, and q =0.01-0.20.

The solubility of the bottom anti-reflective coating materials in safesolvents is an important criterion. The solvent should be capable todissolve the polymer dye material and other additives (surfactants,plasticizers, crosslinking agents) to improve the bottom anti-reflectivecoating film formation properties. From the standpoint of safety,solubility, evaporation ability and film formation, examples ofpreferred solvents include, but are not limited to propylene glycolmonomethyl ether acetate (PGMEA), ethyl lactate (EL), propylene glycolmonomethyl ether, cyclohexanone, cyclopentanone, 2-heptanone andcombinations thereof. The solubility of the polymer dye represented bygeneral formula 1 of the present invention itself can be controlled byproper selection of suitable coreactants R—CHO as depicted in reactionschemes 1 and 2.

Apart from the polymer dye and the solvent the bottom anti-reflectivecoating composition of the present invention may also containsurfactants, crosslinking agents, acid generators, and other additivesto enhance the performance of the coating, and to form a uniform, defectfree film on the semiconductor substrate. As examples of surfactants,fluorinated or siloxane-based compounds can be used but are not limitedto these groups of compounds. The crosslinking agents can be eitherthermal crosslinking agents such as blocked isocyanates, acid catalyzedcrosslinking agents such as the melamine or uracil resins, orepoxy-based crosslinking agents. The acid generators can also be eitherthermal acid generators or photo acid generators.

Another important and desired property of bottom anti-reflectivecoatings is their high etch rates in plasmas and this property is mainlycontrolled by the selection of the polymer dye used in the bottomanti-reflective coating material. It is well known in skilled artists inthe semiconductor industry that a bottom anti-reflective coatingmaterial having significantly higher etch rate than the resist itself inorder to successfully transfer the pattern after exposure and furtherprocessing steps.

The etch rate of an organic material can be calculated by using theOhnishi number or the carbon/hydrogen ratio of the polymer. Since thepolymer materials represented by the general formula 1 contain a highoxygen content and aliphatic carbon moieties, these compounds exhibithigh Ohnishi numbers and are anticipated to have high etch rates. Thisis another merit of this kind of polymer dyes when used as a bottomanti-reflective coating material.

The glass transition temperature of the bottom anti-reflective coatingmaterial plays an important role with respect to substrate coverage andintermixing properties between the bottom anti-reflective coating layerand the applied photoresist. While a relative low glass transitiontemperature is preferred to achieve good step coverage, a higher glasstransition point is preferred with regard to non-intermixing propertiesbetween the bottom anti-reflective coating and photoresist layer. Sincethe photoresist is applied onto the bottom anti-reflective coatinglayer, exposed and developed, any mixing between the alkali-insolublebottom anti-reflective coating layer and the alkali-soluble photoresistwould lead to incomplete removal of the photoresist material upondevelopment usually performed with alkaline developers. Another problemto encounter is that when a chemically amplified photoresist material isapplied on a bottom anti-reflective coating with low glass transitiontemperature the acid formed upon exposure might diffuse into the bottomanti-reflective coating layer leading to a distortion of the latent acidimage and causing incomplete removal of the photoresist material upondevelopment. Therefore, it is desirable that the bottom anti-reflectivecoating material has a glass transition temperature at least above themaximum processing temperatures used while applying the photoresist.This can be controlled in the present invention by manipulating themolar ratio of m, n and o.

The polymer dye content in the anti-reflective coating composition ispreferably in the range of about 1 wt % to about 30 wt %. Preferredconcentration is definitely dependent on the molecular weight of the dyepolymer and the film thickness required to the bottom anti-reflectivecoating. The anti-reflective coating is applied on the substrate usingtechniques well known to those skilled in the art, such as dipping, spincoating, roller coating or spraying. The preferred film thickness of theanti-reflective coating ranges from 30 nm to 1000 nm.

The process of the present invention further comprises coating asubstrate with the bottom anti-reflective coating of the presentinvention and heating on a hotplate or convection oven at a sufficientlyhigh temperature for a sufficient length of time to remove the solventin the coating and to crosslink the polymer to a sufficient extent so asnot to be soluble in the coating solvent of the photoresist or in thealkaline developer. The preferred ranges of temperature and time uponbaking are from about 70° C. to about 280° C. and for 30 seconds to 30minutes. If the temperature is below 70° C. the residual amount ofsolvent is too high or the degree of crosslinking is insufficient. Attemperatures above 280° C. the polymer may become chemically unstable.

The bottom anti-reflective coating is coated on top of the substrate andis further subject to heating and dry etching. It is envisioned that thebottom anti-reflective coating is of sufficiently low metal ion contentso that the electrical properties of the semiconductor device are notadversely affected. Treatments such as passing a solution of the polymerthrough an ion exchange column, filtration and extraction can be used toreduce the concentrations of metal ions or particles.

In the present invention integrated circuits are produced by the waythat positive- or negative-working photoresist sensitive to radiation inthe range of 150 nm-450 nm wavelength is applied onto the bottomanti-reflective coating layer formed by applying the bottomanti-reflective coating composition of the present invention on thesubstrate. After this, the resist layer on the substrate is subjected toexposure and development, and then the image is transferred by wet ordry etching followed by processing necessary for forming the integratedcircuit.

The bottom anti-reflective coating materials of the present inventioncan be preferably applied for both positive- and negative-working resistmaterials. The preferred photoresists include but are by no meanslimited to these examples, one comprising a novolak resin and aphotosensitizer such as quinondiazide and one comprising a substitutedpolyhydroxystyrene and a photo active agent.

BEST MODE FOR CARRYING OUT THE INVENTION

The bottom anti-reflective coating composition of the present invention,the method of manufacturing the composition and the manner of using thecomposition are described in more detail by way of following ApplicationExample and Examples but these examples are only illustrative and notintended to limit or restrict the scope of the invention in any way andshould not be construed as providing conditions, parameters or valueswhich must be utilized exclusively in order to practice the presentinvention.

APPLICATION EXAMPLE

The following general method was used to evaluate the bottomanti-reflective coating compositions of the present invention unlessspecified otherwise:

A 2 wt % solution of the bottom anti-reflective coating material in anappropriate solvent was filtered using 0.5 and 0.2 micron filters, andspin-coated on a 4-inch silicon wafer at a suitable spin speed for 40seconds in such a way that the bottom anti-reflective coatingcomposition has a film thickness of 60 nm after baking at 200° C. for 60seconds. The film was checked with a high resolution microscope toidentify surface defects. The values of the optical constants n(refractive index) and k (absorption parameter) of the film weremeasured on a ellipsometer at the respective wavelengths (248 nm or 356nm).

Then a positive- or negative-working, acid-catalyzed deep UV photoresist(film thickness approximately 700 nm) or a positive- or negative-workingi-line novolak resist (film thickness approximately 1000 nm) was appliedon the bottom anti-reflective coating by spin-coating at a suitable spinspeed for 40 seconds. Depending on the resist material, the resists weresoft baked for 60 seconds at 90-110° C. and exposed on a stepperoperating with an excimer laser (248 nm) source in the case of the deepUV resists or an i-line (356 nm) stepper in the case of the i-lineresist using a reticle with line and space patterns. Following theexposure, the deep UV resists were subjected to a post-exposure bake at90-110° C. The photoresists were developed using a 0.26 N tetramethylammonium hydroxide developer solution for 60 seconds at 23° C. to formthe resist patterns. The resist patterns were examined on a scanningelectron microscopy to check the resolution, standing wave formation,reflective notching, and footing. In order to evaluate the step-coverageproperties of the bottom anti-reflective coating materials, a siliconsubstrate was first coated with a conventional i-line photoresist at afilm thickness of 1000 nm, imagewise exposed, developed and hard-bakedat 200° C. Then the bottom anti-reflective coating material was coatedon the processed wafer having 1000 nm steps provided by the imagedphotoresist. The step-coverage of the bottom anti-reflective coatingthen was analyzed by a scanning electron microscopy. The etch rates ofthe bottom anti-reflective coating materials were evaluated using oxygenand fluoride gas plasmas.

Example 1

Synthesis of a polymer dye starting from polyvinyl alcohol (PVA),anthracene-9-aldehyde (9-AA) and propionaldehyde (PA) and applicationthereof as a bottom anti-reflective coating

22.0 g (0.5 mol) of polyvinyl alcohol (supplied from Wako Pure Chemical,degree of polymerization DP=500), 150 g of ethanol, 25.78 g (0.125 mol)of anthracene-9-aldehyde, 7.26 g (0.125 mol) of propionaldehyde, 0.15 gof 2,6-di-t-butyl-4-methylphenol and 0.25 g of concentrated sulfuricacid were charged into a 300 ml flask. With stirring, the mixture washeated at 70° C. for 8 hours under nitrogen atmosphere. The resultingmixture was cooled and the precipitated solid was filtered, dissolved intetrahydrofuran (THF), and precipitated from THF in water twice. Theresulting yellow powder was dried at 40° C. under vacuum (1 torr). The kvalue of the polymer as measured on an ellipsometer at 248 nm was foundto be 0.4. The polymer was dissolved in cyclohexanone (2 wt % solids),filtered and applied as bottom anti-reflective coating as described inApplication Example. A positive-working deep UV resist AZ® DX 1100available from Clariant (Japan) K.K., was spin-coated, and softbaked at110° C. to yield a film thickness of 755 nm and then exposed using adeep UV stepper (Nikon EX-1OB) attached with a 248 nm KrF laser at adose of 52 mJ/cm². The exposed wafer was baked at 90° C. for 60 seconds,developed using paddle development for 60 seconds at 23° C., rinsed anddried.

Scanning electron microscope inspection of the line and space patternsrevealed that no standing waves are noticed due to the suppression ofreflected light from the substrate by the polymer dye. The resist linepattern profiles were found to be vertical, and the spaces were almostclear showing neither scum nor residues. An etch rate of the bottomanti-reflective coating using an oxygen and trifluoromethane gas plasmaat 60 W was found to be 100 nm/minute.

Examples 2

The procedure of Example 1 was repeated except that positive-workingdeep Uv photoresist AZ® DX 1200P available from Clariant (Japan) K.K.was used as deep UV photoresist and prebake 90° C., film thickness 970nm, dose 28 mJ/cm², and post exposure bake 105° C. were adapted asprocess conditions.

The resulting pattern showed neither footing of the lines nor scum inthe spaces, and their profiles were smooth due to the absence ofstanding waves.

Example 3

The procedure of Example 1 was repeated except that positive-workingdeep UV photoresist AZ® DX 1300P available from Clariant (Japan) K.K.was used as deep UV photoresist and prebake 90° C., film thickness 715nm, dose 13 mJ/cm², and post exposure bake 110° C. were adapted asprocess conditions.

The resulting pattern showed neither footing of the lines nor scum inthe spaces, and their profiles were smooth due to the absence ofstanding waves.

Example 4

Synthesis of a polymer dye starting from polyvinyl alcohol,anthracene-9-aldehyde and propionaldehyde and application thereof as abottom anti-reflective coating

22.0 g (0.5 mol) of polyvinyl alcohol (supplied from Wako Pure ChemicalCo., degree of polymerization 500), 150 g of ethanol, 25.78 g (0.125mol) of anthracene-9-aldehyde, 7.26 g (0.125 mol) of propionaldehyde,0.15 g of 2,6-di-t-butyl-4-methylphenol and 1.20 g of Amberlyst 15(acidic type ion-exchange resin from Fluka A.G., catalyst) were chargedinto a 300 ml flask. The mixture was stirred and heated at 70° C. for 8hours under nitrogen atmosphere. After the solution was cooled to roomtemperature, the solid phase was filtered off and dissolved intetrahydrofuran (THF). The insoluble portion consisting mainly ofAmberlyst 15 was removed and the THF solution was twice precipitatedfrom THF in water. The polymer dye was dried at 40° C. under vacuum (1torr). The k value of the polymer as measured on an ellipsometer at 248nm was found to be 0.39. The polymer was dissolved in cyclohexanone (2wt % solids), filtered and coated as a bottom-anti-reflective coating asdescribed in Application Example. A positive-working deep UV resist AZ®DX 1100 available from Clariant (Japan) K.K. was spin-coated andprocessed as described in Example 1.

The obtained line and space patterns were found to be free from standingwave. The pattern profiles were found to be straight, and the space werefound to be clear with no scum or residues. An etch rate of the bottomanti-reflective coating using oxygen and trifluoromethane gas plasma at60 W was found to be 100 nm/minute.

Examples 5

The procedure of Example 4 was repeated except that positive-workingdeep UV photoresist AZ® DX 2034P available from Clariant (Japan) K.K.was used as deep UV resist and prebake 90° C., film thickness 570 nm,dose 34 mJ/cm², and post-exposure bake 105° C. were adapted as processconditions.

The resulting pattern showed neither footing of the lines nor scum inthe spaces, and their profiles were smooth due to the absence ofstanding waves. The resolution of the deep UV photoresist AZ® DX 2034Pon this bottom anti-reflective coating was better than 0.20 μm.

Example 6

The procedure of Example 4 was repeated except that positive-workingdeep UV photoresist APEX® E avilable from Shipley Corp. was used as deepUV resist and prebake 90° C., film thickness 725 nm, dose 11 mJ/cm², andpost-exposure bake 110° C. were adapted as process conditions.

The resulting pattern showed neither footing of the lines nor scum inthe spaces, and their profiles were smooth due to the absence ofstanding waves.

Example 7

Synthesis of a polymer dye starting from polyvinyl alcohol,anthracene-9-aldehyde and 4-hydroxybenzaldehyde (4-HBA) and applicationthereof as a bottom anti-reflective coating

22.0 g (0.5 mol) of polyvinyl alcohol (supplied from Wako Pure ChemicalCo., degree of polymerization 500), 150 g of ethanol, 25.78 g (0.125mol) of anthracene-9-aldehyde, 13.43 g (0.125 mol) of4-hydroxybenzaldhyde, 0.15 g of 2,6-di-t-butyl-4-methylphenol and 0.25 gof concentrated sulfuric acid were charged into a 300 ml flask. Themixture was stirred and heated at 70° C. for 8 hours under nitrogenatmosphere. The solution was cooled to room temperature, the solid phasewas filtered off and was dissolved in tetrahydrofuran (THF). Insolubleportions were removed and the THF solution was precipitated from THFtwice in water. The product was dried at 40° C. under vacuum (1 torr).The k value of the polymer as measured on an ellipsometer at 248 nm wasfound to be 0.32. The polymer was dissolved in cyclohexanone (2 wt %solids), filtered and coated as bottom anti-reflective coating asdescribed in Application Example. A positive-working deep UV resist AZ®DX 1100 available from Clariant (Japan) K.K. was spin-coated on thebottom anti-reflective coating and processed as described in Example 1.

The bottom anti-reflective coating used in this Example is applicablenot only for exposure with 248 nm KrF laser but also for that with 193nm ArF laser. The k value of the polymer as measured on an ellipsometerat 193 nm was found to be 0.32.

The obtained line and space patterns were found to be free from standingwaves due to the suppression of reflected light from the substrate. Thepattern profiles were found to be straight, and the spaces were found tobe clear with neither scum nor residues. An etch rate of the bottomanti-reflective coating using oxygen and trifluoromethane gas plasma at60 W was found to be 90 nm/minute.

Examples 8

The procedure of Example 7 was repeated except that negative-workingdeep UV photoresist TDUR® N9 available from Tokyo Ohka K. K. was used inplace of deep UV resist AZ® DX1100 and prebake 100° C., film thickness730 nm, dose 44 mJ/cm², and post-exposure bake 130° C. were adapted asprocess conditions.

Example 9

The procedure of Example 7 was repeated except that positive-workingdeep UV photoresist UVIII® available from Shipley Corp. was used inplace of deep UV resist AZ® DX1100 and prebake 130° C., film thickness625 nm, dose 21 mJ/cm², and post-exposure bake 130° C. were adapted asprocess conditions.

Example 10

The procedure of Example 7 was repeated except that positive-workingi-line and deep UV photoresist AZ® PR1024 available from Clariant Corp.was used in place of deep UV resist AZ® DX1100 and prebake 90° C., filmthickness 350 nm, dose of deep UV 32 mJ/cm², and no post-exposure bakewere adapted as process conditions.

All resulting patterns in Examples 8, 9 and 10 showed neither footing ofthe lines nor scum in the spaces, and their profiles were smooth due tothe absence of standing waves.

Example 11

Synthesis of a polymer dye starting from 80% hydrolyzed polyvinylalcohol, anthracene-9-aldehyde and propionaldehyde and applicationthereof as a bottom anti-reflective coating

25 g of polyvinyl alcohol (supplied from Aldrich A.G., weight averagemolecular weight Mw=9,000-10, 000 and hydrolysis degree 80%), 150 g ofethanol, 25.78 g (0.125 mol) of anthracene-9-aldehyde, 7.26 g (0.125mol) of propionaldehyde, 0.15 g of 2,6-di-t-butyl-4-methylphenol and0.25 g of concentrated sulfuric acid were charged into a 300 ml flask.The mixture was stirred and heated at 70° C. for 8 hours under nitrogenatmosphere. After the solution was cooled, it was diluted with ethanol.The solid phase was filtered off and dissolved in THF. The THF solutionwas twice precipitated in water. The polymer dye obtained was dried at40° C. under vacuum (1 torr). The k value of the polymer as measured onan ellipsometer at 248 nm was found to be 0.35. The polymer wasdissolved in ethyl lactate (2 wt % solids), filtered and coated as abottom-anti-reflective coating as described in Application Example. Apositive-working deep UV resist AZ® DX 1100 available from Clariant(Japan) K.K. was spin-coated and processed as described in Example 1.The resulting pattern showed neither standing wave in the lines nor scumor residues in the spaces.

Example 12

Negative-working deep UV resist with following constitution was appliedon the bottom anti-reflective coating described in Example 11.

(constitution) (part by weight) 4-hydroxystyrene/styrene (8/2) copolymer80 (weight average molecular weight 12,000) hexamethoxymethylmeramine(distilled) 20 tribromomethylphenylsulfone 1 tributyl amine 0.1

The resist applied on the substrate was soft-baked for 60 seconds at110° C., exposed at dose of 24 mJ/cm², post-exposed at 120° C. for 60seconds and processed as described in Example 1. Under these conditionssome scum (footing) in the unexposed areas was observed. Therefore, a 5wt % Kronate® thermal crosslinking agent (available from NipponPolyurethane K. K.) was added to the bottom anti-reflective coatingsolution described in Example 11 and the resultant composition was usedin place of the bottom anti-reflective coating composition described inExample 11 and processed as described above. This time, the line andspace patterns were found to be free from standing waves. The patternprofiles were found to be straight and the space was found to be clearwith no scum.

An etch rate of the bottom anti-reflective coating using oxygen andtrifluoromethane gas plasma at 60 W was found to be 105 nm/minute.Example 13: Synthesis of a polymer dye starting from poly(vinylalcohol-co-ethylene) [PVA-ET], anthracene-9-aldehyde and propionaldehydeand application thereof as a bottom anti-reflective coating

22 g of poly(vinyl alcohol-co-ethylene) (obtained from Aldrich Co.,ethylene content 27 mol %), 150 g of o-xylene, 25.78 g (0.125 mol) ofanthracene-9-aldehyde, 3.6 g (0.063 mol) of propionaldehyde, 0.15 g of2,6-di-t-butyl-4-methylphenol and 0.25 g of concentrated sulfuric acidwere charged into a 300 ml flask. The mixture was stirred and heated at120° C. for 8 hours under nitrogen atmosphere. The solution was cooled,diluted, and filtered. The viscous solution obtained was twiceprecipitated in a 70:30 v/v ethanol:water mixture. The polymer was driedat 40° C. under vacuum (1 torr). The k value of the polymer as measuredon an ellipsometer at 248 nm was found to be 0.38. The polymer wasdissolved in ethyl lactate (2 wt % solids), filtered and doated asbottom-anti-reflective coating as described in the general applicationexample. A positive-working deep UV resist AZ® DX 1100 available fromClariant (Japan) K.K. was spin-coated on the bottom anti-reflectivecoating and processed as described in Example 1.

The obtained line and space patterns were found to be free from standingwaves due to suppression of reflected light from the substrate. Thepattern profiles were found to be straight and the space was found to beclear with no scum or residues.

Similar results were obtained with the positive-working deep UVphotoresist AZ® DX 2034 as well as a negative-working resist describedin Example 12. An etch rate of the bottom anti-reflective coatingmaterial using oxygen and trifluoromethane gas plasma at 60 W was foundto be 90 nm/minute.

Comparative Example 1

Synthesis of a polymer dye starting from polyvinyl alcohol andanthracene-9-aldehyde and application thereof as a bottomanti-reflective coating

22.0 g (0.5 mol) of polyvinyl alcohol (supplied from Wako Pure ChemicalCo., degree of polymerization 500), 150 g of ethanol, 25.78 g (0.125mol) of anthracene-9-aldehyde, 0.15 g 2,6-di-t-butyl-4-methylphenol and0.25 g of concentrated sulfuric acid were charged into a 300 ml flask.The mixture was stirred and heated at 70° C. for 8 hours under nitrogenatmosphere. The resulting mixture was cooled and the precipitated solidwas filtered and dissolved in tetrahydrofuran (THF). Small amount ofinsoluble portion was removed and the THF solution was precipitated fromTHF in water twice. The resulting yellow powder was dried at 40° C.under vacuum (1 torr). The k value of the polymer as measured on anellipsometer at 248 nm was found to be 0.42. The polymer was dissolvedin cyclohexanone (2 wt % solids), filtered and coated as bottomanti-reflective coating as described in Application Example. Apositive-working deep UV resist AZ® DX 1100 available from Clariant(Japan) K. K. was spin-coated on the anti-reflective coating andprocessed as described in Example 1.

In the line and space patterns no standing waves was observed due to thesuppression of reflected light from the substrate. The resist patternprofiles were found to be vertical, and the spaces were clear showingneither scum nor residues. An etch rate of the bottom anti-reflectivecoating using an oxygen and trifluoromethane gas plasma at 60 W wasfound to be 105 nm/minute.

Comparative Example 2

The procedure of Comparative Example 1 was repeated except thatpolyvinyl alcohol (supplied from Wako Pure Chemical Co., degree ofpolymerization 1000) was used in the synthesis in place of polyvinylalcohol (supplied from Wako Pure Chemical Co., degree of polymerization500).

Comparative Example 3

The procedure of Comparative Example 1 was repeated except thatpartially hydrolyzed polyvinyl alcohol (supplied from Wako Pure ChemicalCo., degree of polymerization 1000) was used in the synthesis in placeof polyvinyl alcohol (supplied from Wako Pure Chemical Co., degree ofpolymerization 500).

Comparative Example 4

The procedure of Comparative Example 1 was repeated except thatpartially hydrolyzed polyvinyl alcohol (supplied from Wako Pure ChemicalCo., degree of polymerization 2800) was used in the synthesis in placeof polyvinyl alcohol (supplied from Wako Pure Chemical Co., degree ofpolymerization 500).

Comparative Example 5

The procedure of Comparative Example 1 was repeated except thatpartially hydrolyzed polyvinyl alcohol (supplied from Wako Pure ChemicalCo., degree of polymerization 3500) was used in the synthesis in placeof polyvinyl alcohol (supplied from Wako Pure Chemical Co., degree ofpolymerization 500).

In all cases of Comparative Examples 2 to 5 neither footing of the linesnor scum in the spaces were observed, and the photoresist profiles weresmooth due to the absence of standing waves. However, it was found thatthe step coverage properties became inferior in proportion to theincrease of degree of polymerization. As the result, it was seen thatthe polymer dye formed using higher degree of polymerization polymershowed a tendency of inferior film formation along the stepped surface.

Yields of acetalization reactions in Examples 1, 4, 7, 11 and 13 andComparative Examples 1 to 5 are shown in following table 1.

TABLE 1 Reaction Reaction temperature time Yield* Backbone polymer D-CHOR-CHO (° C.) (hour) (%) Special mention Example 1 PVA DP = 500 9-AA PA70 8 116 Example 4 PVA DP = 500 9-AA PA 70 8 132 Example 7 PVA DP = 5009-AA 4-HBA 70 8 126 Example 11 PVA Mw = 9-AA PA 70 8 118 9000˜10000 80%hydrolyzed Example 13 PVA-Et 9-AA PA 120  8 128 (Et = 27 mol %)Comparative PVA DP = 500 9-AA — 70 8  60 Separation of solid phaseExample 1 and liquid phase was difficult Comparative PVA DP = 1000 9-AA— 70 8  78 Separation of solid phase Example 2 and liquid phase wasdifficult Comparative PVA DP = 1000 9-AA — 70 8 100 Separation of solidphase Example 3 Partially saponified and liquid phase was difficultComparative PVA DP = 2800 9-AA — 70 8  82 Separation of solid phaseExample 4 Partially saponified and liquid phase was difficultComparative PVA DP = 3500 9-AA — 70 8  80 Separation of solid phaseExample 5 Partially saponified and liquid phase was difficult *wt %based on weight of charged PVA

It is clearly understood from table 1 that the yield of reaction productusing both an alkyl or benzaldehyde derivative and anthracene-9-aldehydeis higher than that using only anthracene-9-aldehyde.

Effect of the Invention

In the present invention solvents used in formation of the photoresistlayer can be utilized as a solvent of the bottom anti-reflective coatingcomposition, and the bottom anti-reflective coating composition of thepresent invention has good storage stability, excellent film formationproperties and excellent step coverage properties. In addition, sincethe bottom anti-reflective coating formed by using the bottomanti-reflective coating composition of the present invention revealshigh absorption at exposure wavelength radiation, there is no problem ofstanding wave formation or reflective notching as well as intermixingbetween the photoresist layer and the bottom anti-reflective coating.Further the bottom anti-reflective coating of the present invention hashigh etch rate. Therefore fine resist patterns with high resolution andgood pattern shape can be formed by using the bottom anti-reflectivecoating composition of the present invention and integrated circuitshaving desirable degree of integration can be manufactured with ease byprocessing the semiconductor substrate with the fine resist patterns.

Industrial applicability

As has been described hereinbefore, the novel polymer dyes of thepresent invention can be used as bottom anti-reflective coatingmaterials and by use of the bottom anti-reflective coating compositioncomprising the novel polymer dye, integrated circuits with high degreeof integration can be formed easily and in high yield.

What is claimed is:
 1. A bottom anti-reflective coating composition foruse in photolithography which comprises at least a solvent and a polymerdye represented by general formula 1:

wherein R represents a hydrogen atom, a substituted or non-substitutedC₁-C₂₀ alkyl group, a substituted or non-substituted C₆-C₂₀ cycloalkylgroup, or a substituted or non-substituted C₆-C₂₀ aryl group, R¹represents a hydrogen atom, a substituted or non-substituted C₁-C₅ alkylgroup, a substituted or non-substituted C₆-C₁₀ aryl group, or a —COOR³group in which R³ represents a C₁-C₁₀ alkyl group, R² represents asubstituted or non-substituted C₁-C₅ alkyl group, a substituted ornon-substituted C₆-C₂₀ cycloalkyl group, or a substituted ornon-substituted C₆-C₂₀ aryl group, D is an organic chromophore whichabsorbs at the exposure wavelength (150-450 nm) and represents asubstituted or non-substituted C₆-C₃₀ aryl group, a substituted ornon-substituted C₆-C₃₀ condensed aryl group, or a substituted ornon-substituted C₄-C₃₀ heteroaryl group, m and o are any integer abovezero, and n, p and q are any integer including zero.
 2. The bottomanti-reflective coating composition according to claim 1 wherein Drepresents phenyl, substituted phenyl, benzyl, substituted benzyl,naphthyl, substituted naphthyl, anthracenyl, substituted anthracenyl,anthraquinonyl, substituted anthraquinonyl, acridinyl, substitutedacridinyl, azophenyl, substituted azophenyl, fluorenyl, substitutedfluorenyl, fluorenonyl, substituted fluorenonyl, carbazolyl, substitutedcarbazolyl, N-alkylcarbazolyl, dibenzofuranyl, substituteddibenzofuranyl, phenanthrenyl, substituted phenanthrenyl, pyrenyl, orsubstituted pyrenyl, and the substitution is optionally selected fromone or more of the following groups; linear, branched or cyclic C₁-C₂₀alkyl, C₆-C₂₀ aryl, halogen, C₁-C₂₀ alkyloxy, nitro, carbonyl, cyano,amide, sulfonamide, imide, carboxylic acid, carboxylic acid ester,sulfonic acid, sulfonic acid ester, C₁-C₁₀ alkylamine, or C₆-C₂₀arylamine.
 3. The bottom anti-reflective coating composition accordingto claim 1 wherein R represents either hydrogen, methyl, ethyl, propyl,butyl, nitrophenyl, hydroxyphenyl, or methoxyphenyl.
 4. The bottomanti-reflective coating composition according to claim 1 wherein R²represents methyl, ethyl, propyl, phenyl, naphthyl, or anthracenyl. 5.The bottom ant-reflective coating composition according to claim 1wherein D represents substituted or non-substituted phenyl, naphthyl oranthracenyl.
 6. The bottom anti-reflective coating composition accordingto claim 5 wherein p is zero.
 7. The bottom anti-reflective coatingcomposition according to claim 1 wherein the polymer dye represented bythe general formula 1 has a weight average molecular weight (Mw) between2,000 to 200,000.
 8. The bottom anti-reflective coating compositionaccording to claim 1 wherein 50 to 95 parts by weight of the solids arethe polymer dye represented in the general formula 1 and 50 to 5 partsby weight are a thermal crosslinking agent.
 9. The bottomanti-reflective coating composition according to claim 8 wherein thecrosslinking agent is either melamine, blocked isocyanate, uracil, orepoxy type crosslinking agent.
 10. The bottom anti-reflective coatingcomposition according to claim 1 wherein 50 to 95 parts by weight of thesolids are the polymer dye represented by the general formula 1, 50 to 5parts by weight are a thermal crosslinking agent and 1 to 10 parts byweight of solids are an acid generator.
 11. The bottom anti-reflectivecoating composition according to claim 10 wherein the crosslinking agentis either melamine, blocked isocyanate, uracil, or epoxy typecrosslinking agent and the acid generator is either an onium salt, adiazomethane compound or a nitrobenzyl tosylate.
 12. The bottomanti-reflective coating composition according to claim 1 wherein thepolymer dye represented by the general formula 1 are dissolved in 1 to10 wt % concentration in cyclohexanone, propylene glycol monomethylether acetate, ethyl lactate, methyl amyl ketone, or a mixture of thesesolvents.
 13. A method of producing an anti-reflective coating on asemiconductor substrate which comprises the following steps: a)dissolving at least the polymer dye represented by the general formula 1described in claim 1 in an organic solvent, b) filtering the solutionand then spin-, spray-, dip-, or roller-coating the solution onto asemiconductor substrate, and c) thermally removing the solvent to form asubstrate coated with a bottom anti-reflective coating compositiondescribed in claim
 1. 14. A method of manufacturing integrated circuitsin which a positive- or negative-working photoresist sensitive toradiation in the range of 150 nm to 450 nm is applied on a semiconductorsubstrate coated with a thin layer of a bottom anti-reflective coatingcomposition of claim 1, and the resist coated substrate is exposed withradiation, developed, and etched by dry or wet etching process totransferred the image on to the substrate.
 15. The method ofmanufacturing integrated circuits according to claim 14 wherein thephotoresist comprises a novolak resin, a photosensitive compound and asolvent.
 16. The method of manufacturing integrated circuits accordingto claim 14 wherein the photoresist comprises a substitutedpolyhydroxystyrene, a photo-active compound and a solvent.
 17. A polymerdye represented by general formula 1:

wherein R represents a hydrogen atom, a substituted or non-substitutedC₁-C₂₀ alkyl group, a substituted or non-substituted C₆-C₂₀ cycloalkylgroup, or a substituted or non-substituted C₆-C₂₀ aryl group, R¹represents a hydrogen atom, a substituted or non-substituted C₁-C₅ alkylgroup, a substituted or non-substituted C₆-C₁ aryl group, or a —COOR³group in which R³ represents a C₁-C₁₀ alkyl group, R² represents asubstituted or non-substituted C₁-C₅ alkyl group, a substituted ornon-substituted C₆-C₂₀ cycloalkyl group, or a substituted ornon-substituted C₆-C₂₀ aryl group, D is an organic chromophore whichabsorbs at the exposure wavelength (150-450 nm) and represents asubstituted or non-substituted C₆-C₃₀ aryl group, a substituted ornon-substituted C₆-C₃₀ condensed aryl group, or a substituted ornon-substituted C₄-C₃₀ heteroaryl group, m and o are any integer abovezero, and n, p and q are any integer including zero.
 18. A method ofproducing the polymer dye represented by the general formula 1 describedin claim 17.